Day 18 – Atari 400, SIO2SD, and Composite fail

RC2016/10 Day 18.

For some reason, October is the month where everything wants to be worked on. It’s been over a week since I’ve gotten some “retro time” so i decided to break out the Atari 400.

My Atari 400
Say what you will about it, but this picture won me $250 in Sophos’s retro week contest.

I’ve had this Atari 400 since I was probably about 8 years old. My dad had the first go at it with a soldering iron, taking it to 48k of RAM and adding that spectacular external 800 keyboard (in a hand-made case, no less). I did a quick-and-dirty composite video mod to this machine about 3 years ago so I could bring it to a retro gaming night, but the output was barely visible on the screen. So, this thing needs some love.

Shortly after “Brexit”, when the dollar gained nicely against the Euro, I purchased an SIO2SD and a stereo pokey mod from Lotharek. I also bought a second pokey chip from him, and he installed it in the stereo board for me automatically. Nice.

Stereo pokey mode
Am I the only one who calls this a Gumby mod?

For the SIO2SD, I went cheap and bought the bare board. I already have a chopped up SIO cable on the homebrew cassette interface that my dad built for the Atari. I can’t remember if we used the tape before getting the 810 disk drive, or if we just wanted to have the tape interface. I remember playing some educational games on tape and saving some BASIC type-ins to tape as well. Anyway, with this guy, I won’t need tapes anymore, so I can scrounge the SIO cable from it.

SIO2SD board before attaching the LCD module to the top header.

A few minutes of wire stripping (I love screw terminals) and I have an SIO2SD attached to my Atari. Time to play some games I haven’t played in over 25 years.


Rats! Seems like the video signal from my composite mod is too crappy for this old LCD monitor to recognize. Time to break out the big guns.


Crud. No dice with the Magnavox CRT TV either. Guess either something’s come loose inside or my mod was even worse than I’d realized.

In any case, the Atari project will have to go back on hold until I can either redo the mod myself or install a video mod board. I’m really hoping that Bryan from AtariAge gets his Ultimate Atari Video board back into production. He’s re-working rev. D right now. If I have to wait much longer, I’ll probably just get a 7800 mod board from eBay and stuff it in as a stopgap.